充电式混合动力汽车只能保证第一次充电是全电动的；最终还是要使用汽油引擎。

Plug-in hybrid cars can only travel so far on a charge; eventually, the gasoline engine kicks in.

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全电动汽车不使用汽油，但是它们的碳排放情况取决于它们什么时候充电。

All-electric cars use no gas, but their carbon profiles depend on when they plug in.

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在全电模式下，通用公司的这款汽车预计行可行驶50英里(合80公里)，足以满足大多数美国通勤者的需求，这样他们只在跑长途的情况下才需要使用汽油发动机。

GM's car is expected to go around 50 miles (80km) in all-electric mode, more than enough for most American commuters, who would need to use the petrol engine on longer trips only.

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